Varicella zoster virus productively infects human peripheral blood mononuclear cells to modulate expression of immunoinhibitory proteins and blocking PD-L1 enhances virus-specific CD8+ T cell effector function.

Varicella zoster virus (VZV) is a lymphotropic alpha-herpesvirinae subfamily member that produces varicella on primary infection and causes zoster, vascular disease and vision loss upon reactivation from latency. VZV-infected peripheral blood mononuclear cells (PBMCs) disseminate virus to distal organs to produce clinical disease. To assess immune evasion strategies elicited by VZV that may contribute to dissemination of infection, human PBMCs and VZV-specific CD8+ T cells (V-CD8+) were mock- or VZV-infected and analyzed for immunoinhibitory protein PD-1, PD-L1, PD-L2, CTLA-4, LAG-3 and TIM-3 expression using flow cytometry. All VZV-infected PBMCs (monocytes, NK, NKT, B cells, CD4+ and CD8+ T cells) and V-CD8+ showed significant elevations in PD-L1 expression compared to uninfected cells. VZV induced PD-L2 expression in B cells and V-CD8+. Only VZV-infected CD8+ T cells, NKT cells and V-CD8+ upregulated PD-1 expression, the immunoinhibitory receptor for PD-L1/PD-L2. VZV induced CTLA-4 expression only in V-CD8+ and no significant changes in LAG-3 or TIM-3 expression were observed in V-CD8+ or PBMC T cells. To test whether PD-L1, PD-L2 or CTLA-4 regulates V-CD8+ effector function, autologous PBMCs were VZV-infected and co-cultured with V-CD8+ cells in the presence of blocking antibodies against PD-L1, PD-L2 or CTLA-4; ELISAs revealed significant elevations in IFNγ only upon blocking of PD-L1. Together, these results identified additional immune cells that are permissive to VZV infection (monocytes, B cells and NKT cells); along with a novel mechanism for inhibiting CD8+ T cell effector function through induction of PD-L1 expression.

Varicella Zoster Virus Alters Expression of Cell Adhesion Proteins in Human Perineurial Cells via Interleukin 6.

BACKGROUND: In temporal arteries (TAs) from patients with giant cell arteritis, varicella zoster virus (VZV) is seen in perineurial cells that surround adventitial nerve bundles and form the peripheral nerve-extrafascicular tissue barrier (perineurium). We hypothesized that during VZV reactivation from ganglia, virus travels transaxonally and disrupts the perineurium to infect surrounding cells. METHODS: Mock- and VZV-infected primary human perineurial cells (HPNCs) were examined for alterations in claudin-1, E-cadherin, and N-cadherin. Conditioned supernatant was analyzed for a soluble factor(s) mediating these alterations and for the ability to increase cell migration. To corroborate in vitro findings, a VZV-infected TA was examined. RESULTS: In VZV-infected HPNCs, claudin-1 redistributed to the nucleus; E-cadherin was lost and N-cadherin gained, with similar changes seen in VZV-infected perineurial cells in a TA. VZV-conditioned supernatant contained increased interleukin 6 (IL-6) that induced E-cadherin loss and N-cadherin gain and increased cell migration when added to uninfected HPNCs; anti-IL-6 receptor antibody prevented these changes. CONCLUSIONS: IL-6 secreted from VZV-infected HPNCs facilitated changes in E- and N-cadherin expression and cell migration, reminiscent of an epithelial-to-mesenchymal cell transition, potentially contributing to loss of perineurial cell barrier integrity and viral spread. Importantly, an anti-IL-6 receptor antibody prevented virus-induced perineurial cell disruption.

Varicella Zoster Virus Induces Nuclear Translocation of the Neurokinin-1 Receptor, Promoting Lamellipodia Formation and Viral Spread in Spinal Astrocytes.

Background: Varicella zoster virus (VZV) can present as a myelopathy with spinal astrocyte infection. Recent studies support a role for the neurokinin-1 receptor (NK-1R) in virus infections, as well as for cytoskeletal alterations that may promote viral spread. Thus, we examined the role of NK-1R in VZV-infected primary human spinal astrocytes (HA-sps) to shed light on the pathogenesis of VZV myelopathy. Methods: Mock- and VZV-infected HA-sps were examined for substance P (subP) production, NK-1R localization, morphological changes, and viral spread in the presence or absence of the NK-1R antagonists aprepitant and rolapitant. Results: VZV infection of HA-sps induced nuclear localization of full-length and truncated NK-1R in the absence of the endogenous ligand, subP, and was associated with extensive lamellipodia formation and viral spread that was inhibited by NK-1R antagonists. Conclusions: We have identified a novel, subP-independent, proviral function of nuclear NK-1R associated with lamellipodia formation and viral spread that is distinct from subP-induced NK-1R cell membrane/cytoplasmic localization without lamellipodia formation. These results suggest that binding of a putative viral ligand to NK-1R produces a dramatically different NK-1R downstream effect than binding of subP. Finally, the NK-1R antagonists aprepitant and rolapitant provide promising alternatives to nucleoside analogs in treating VZV infections, including myelopathy.

Tetraspanin CD9 and ectonucleotidase CD73 identify an osteochondroprogenitor population with elevated osteogenic properties.

Cell-based bone regeneration strategies offer promise for traumatic bone injuries, congenital defects, non-union fractures and other skeletal pathologies. Postnatal bone remodeling and fracture healing provide evidence that an osteochondroprogenitor cell is present in adult life that can differentiate to remodel or repair the fractured bone. However, cell-based skeletal repair in the clinic is still in its infancy, mostly due to poor characterization of progenitor cells and lack of knowledge about their in vivo behavior. Here, we took a combined approach of high-throughput screening, flow-based cell sorting and in vivo transplantation to isolate markers that identify osteochondroprogenitor cells. We show that the presence of tetraspanin CD9 enriches for osteochondroprogenitors within CD105(+) mesenchymal cells and that these cells readily form bone upon transplantation. In addition, we have used Thy1.2 and the ectonucleotidase CD73 to identify subsets within the CD9(+) population that lead to endochondral or intramembranous-like bone formation. Utilization of this unique cell surface phenotype to enrich for osteochondroprogenitor cells will allow for further characterization of the molecular mechanisms that regulate their osteogenic properties.

Varicella zoster virus differentially alters morphology and suppresses proinflammatory cytokines in primary human spinal cord and hippocampal astrocytes.

BACKGROUND: Varicella zoster virus (VZV) is a ubiquitous alphaherpesvirus that produces varicella and zoster. VZV can infect multiple cell types in the spinal cord and brain, including astrocytes, producing myelopathy and encephalopathy. While studies of VZV-astrocyte interactions are sparse, a recent report showed that quiescent primary human spinal cord astrocytes (qHA-sps) did not appear activated morphologically during VZV infection. Since astrocytes play a critical role in host defenses during viral infections of the central nervous system, we examined the cytokine responses of qHA-sps and quiescent primary human hippocampal astrocytes (qHA-hps) to VZV infection in vitro, as well as the ability of conditioned supernatant to recruit immune cells. METHODS: At 3 days post-infection, mock- and VZV-infected qHA-sps and qHA-hps were examined for morphological changes by immunofluorescence antibody assay using antibodies directed against glial fibrillary acidic protein and VZV. Conditioned supernatants were analyzed for proinflammatory cytokines [interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, interferon-gamma, and tumor necrosis factor-α] using the Meso Scale Discovery multiplex ELISA platform. Finally, the ability of conditioned supernatants to attract peripheral blood mononuclear cells (PBMCs) was determined using a chemotaxis assay. Quiescent primary human perineurial cells (qHPNCs) served as a control for VZV-induced cytokine production and PBMC migration. To confirm that the astrocytes have the ability to increase cytokine secretion, qHA-sps and qHA-hps were treated with IL-1ß and examined for morphological changes and IL-6 secretion. RESULTS: VZV-infected qHA-sps displayed extensive cellular processes, whereas VZV-infected qHA-hps became swollen and clustered together. Astrocytes had the capacity to secrete IL-6 in response to IL-1ß. Compared to mock-infected cells, VZV-infected qHA-sps showed significantly reduced secretion of IL-2, IL-4, IL-6, IL-12p70, and IL-13, while VZV-infected qHA-hps showed significantly reduced IL-8 secretion. In contrast, levels of all 10 cytokines examined were significantly increased in VZV-infected qHPNCs. Consistent with these results, conditioned supernatant from VZV-infected qHPNCs, but not that from VZV-infected qHA-sps and qHA-hps, recruited PBMCs. CONCLUSIONS: VZV-infected qHA-sps and qHA-hps have distinct morphological alterations and patterns of proinflammatory cytokine suppression that could contribute to ineffective viral clearance in VZV myelopathy and encephalopathy, respectively.

Targeted Genome Sequencing Reveals Varicella-Zoster Virus Open Reading Frame 12 Deletion.

The neurotropic herpesvirus varicella-zoster virus (VZV) establishes a lifelong latent infection in humans following primary infection. The low abundance of VZV nucleic acids in human neurons has hindered an understanding of the mechanisms that regulate viral gene transcription during latency. To overcome this critical barrier, we optimized a targeted capture protocol to enrich VZV DNA and cDNA prior to whole-genome/transcriptome sequence analysis. Since the VZV genome is remarkably stable, it was surprising to detect that VZV32, a VZV laboratory strain with no discernible growth defect in tissue culture, contained a 2,158-bp deletion in open reading frame (ORF) 12. Consequently, ORF 12 and 13 protein expression was abolished and Akt phosphorylation was inhibited. The discovery of the ORF 12 deletion, revealed through targeted genome sequencing analysis, points to the need to authenticate the VZV genome when the virus is propagated in tissue culture.IMPORTANCE Viruses isolated from clinical samples often undergo genetic modifications when cultured in the laboratory. Historically, VZV is among the most genetically stable herpesviruses, a notion supported by more than 60 complete genome sequences from multiple isolates and following multiple in vitro passages. However, application of enrichment protocols to targeted genome sequencing revealed the unexpected deletion of a significant portion of VZV ORF 12 following propagation in cultured human fibroblast cells. While the enrichment protocol did not introduce bias in either the virus genome or transcriptome, the findings indicate the need for authentication of VZV by sequencing when the virus is propagated in tissue culture.

QQS orphan gene regulates carbon and nitrogen partitioning across species via NF-YC interactions.

The allocation of carbon and nitrogen resources to the synthesis of plant proteins, carbohydrates, and lipids is complex and under the control of many genes; much remains to be understood about this process. QQS (Qua-Quine Starch; At3g30720), an orphan gene unique to Arabidopsis thaliana, regulates metabolic processes affecting carbon and nitrogen partitioning among proteins and carbohydrates, modulating leaf and seed composition in Arabidopsis and soybean. Here the universality of QQS function in modulating carbon and nitrogen allocation is exemplified by a series of transgenic experiments. We show that ectopic expression of QQS increases soybean protein independent of the genetic background and original protein content of the cultivar. Furthermore, transgenic QQS expression increases the protein content of maize, a C4 species (a species that uses 4-carbon photosynthesis), and rice, a protein-poor agronomic crop, both highly divergent from Arabidopsis. We determine that QQS protein binds to the transcriptional regulator AtNF-YC4 (Arabidopsis nuclear factor Y, subunit C4). Overexpression of AtNF-YC4 in Arabidopsis mimics the QQS-overexpression phenotype, increasing protein and decreasing starch levels. NF-YC, a component of the NF-Y complex, is conserved across eukaryotes. The NF-YC4 homologs of soybean, rice, and maize also bind to QQS, which provides an explanation of how QQS can act in species where it does not occur endogenously. These findings are, to our knowledge, the first insight into the mechanism of action of QQS in modulating carbon and nitrogen allocation across species. They have major implications for the emergence and function of orphan genes, and identify a nontransgenic strategy for modulating protein levels in crop species, a trait of great agronomic significance.

Integrating metabolomics and transcriptomics data to discover a biocatalyst that can generate the amine precursors for alkamide biosynthesis.

The Echinacea genus is exemplary of over 30 plant families that produce a set of bioactive amides, called alkamides. The Echinacea alkamides may be assembled from two distinct moieties, a branched-chain amine that is acylated with a novel polyunsaturated fatty acid. In this study we identified the potential enzymological source of the amine moiety as a pyridoxal phosphate-dependent decarboxylating enzyme that uses branched-chain amino acids as substrate. This identification was based on a correlative analysis of the transcriptomes and metabolomes of 36 different E. purpurea tissues and organs, which expressed distinct alkamide profiles. Although no correlation was found between the accumulation patterns of the alkamides and their putative metabolic precursors (i.e., fatty acids and branched-chain amino acids), isotope labeling analyses supported the transformation of valine and isoleucine to isobutylamine and 2-methylbutylamine as reactions of alkamide biosynthesis. Sequence homology identified the pyridoxal phosphate-dependent decarboxylase-like proteins in the translated proteome of E. purpurea. These sequences were prioritized for direct characterization by correlating their transcript levels with alkamide accumulation patterns in different organs and tissues, and this multi-pronged approach led to the identification and characterization of a branched-chain amino acid decarboxylase, which would appear to be responsible for generating the amine moieties of naturally occurring alkamides.

Varicella-Zoster Virus Downregulates Programmed Death Ligand 1 and Major Histocompatibility Complex Class I in Human Brain Vascular Adventitial Fibroblasts, Perineurial Cells, and Lung Fibroblasts.

Varicella-zoster virus (VZV) vasculopathy produces stroke, giant cell arteritis, and granulomatous aortitis, and it develops after virus reactivates from ganglia and spreads transaxonally to arterial adventitia, resulting in persistent inflammation and pathological vascular remodeling. The mechanism(s) by which inflammatory cells persist in VZV-infected arteries is unknown; however, virus-induced dysregulation of programmed death ligand 1 (PD-L1) may play a role. Specifically, PD-L1 can be expressed on virtually all nucleated cells and suppresses the immune system by interacting with the programmed cell death protein receptor 1, found exclusively on immune cells; thus, downregulation of PD-L1 may promote inflammation, as seen in some autoimmune diseases. Both flow cytometry and immunofluorescence analyses to test whether VZV infection of adventitial cells downregulates PD-L1 showed decreased PD-L1 expression in VZV-infected compared to mock-infected human brain vascular adventitial fibroblasts (HBVAFs), perineural cells (HPNCs), and fetal lung fibroblasts (HFLs) at 72 h postinfection. Quantitative RT-PCR analyses showed no change in PD-L1 transcript levels between mock- and VZV-infected cells, indicating a posttranscriptional mechanism for VZV-mediated downregulation of PD-L1. Flow cytometry analyses showed decreased major histocompatibility complex class I (MHC-I) expression in VZV-infected cells and adjacent uninfected cells compared to mock-infected cells. These data suggest that reduced PD-L1 expression in VZV-infected adventitial cells contribute to persistent vascular inflammation observed in virus-infected arteries from patients with VZV vasculopathy, while downregulation of MHC-I prevents viral clearance. IMPORTANCE: Here, we provide the first demonstration that VZV downregulates PD-L1 expression in infected HBVAFs, HPNCs, and HFLs, which, together with the noted VZV-mediated downregulation of MHC-I, might foster persistent inflammation in vessels, leading to pathological vascular remodeling during VZV vasculopathy and persistent inflammation in infected lungs to promote subsequent infection of T cells and hematogenous virus spread. Identification of a potential mechanism by which persistent inflammation in the absence of effective viral clearance occurs in VZV vasculopathy and VZV infection of the lung is a step toward targeted therapy of VZV-induced disease.

Dampening of death pathways by schnurri-2 is essential for T-cell development.

Generation of a diverse and self-tolerant T-cell repertoire requires appropriate interpretation of T-cell antigen receptor (TCR) signals by CD4(+ ) CD8(+) double-positive thymocytes. Thymocyte cell fate is dictated by the nature of TCR-major-histocompatibility-complex (MHC)-peptide interactions, with signals of higher strength leading to death (negative selection) and signals of intermediate strength leading to differentiation (positive selection). Molecules that regulate T-cell development by modulating TCR signal strength have been described but components that specifically define the boundaries between positive and negative selection remain unknown. Here we show in mice that repression of TCR-induced death pathways is critical for proper interpretation of positive selecting signals in vivo, and identify schnurri-2 (Shn2; also known as Hivep2) as a crucial death dampener. Our results indicate that Shn2(-/-) double-positive thymocytes inappropriately undergo negative selection in response to positive selecting signals, thus leading to disrupted T-cell development. Shn2(-/-) double-positive thymocytes are more sensitive to TCR-induced death in vitro and die in response to positive selection interactions in vivo. However, Shn2-deficient thymocytes can be positively selected when TCR-induced death is genetically ablated. Shn2 levels increase after TCR stimulation, indicating that integration of multiple TCR-MHC-peptide interactions may fine-tune the death threshold. Mechanistically, Shn2 functions downstream of TCR proximal signalling compenents to dampen Bax activation and the mitochondrial death pathway. Our findings uncover a critical regulator of T-cell development that controls the balance between death and differentiation.

Control of bone resorption in mice by Schnurri-3.

Mice lacking the large zinc finger protein Schnurri-3 (Shn3) display increased bone mass, in part, attributable to augmented osteoblastic bone formation. Here, we show that in addition to regulating bone formation, Shn3 indirectly controls bone resorption by osteoclasts in vivo. Although Shn3 plays no cell-intrinsic role in osteoclasts, Shn3-deficient animals show decreased serum markers of bone turnover. Mesenchymal cells lacking Shn3 are defective in promoting osteoclastogenesis in response to selective stimuli, likely attributable to reduced expression of the key osteoclastogenic factor receptor activator of nuclear factor-κB ligand. The bone phenotype of Shn3-deficient mice becomes more pronounced with age, and mice lacking Shn3 are completely resistant to disuse osteopenia, a process that requires functional osteoclasts. Finally, selective deletion of Shn3 in the mesenchymal lineage recapitulates the high bone mass phenotype of global Shn3 KO mice, including reduced osteoclastic bone catabolism in vivo, indicating that Shn3 expression in mesenchymal cells directly controls osteoblastic bone formation and indirectly regulates osteoclastic bone resorption.

Emerging roles of PPARs in inflammation and immunity.

Lipids and lipid metabolism have well-documented regulatory effects on inflammatory processes. Recent work has highlighted the role of the peroxisome proliferator-activated receptors (PPARs)--a subset of the nuclear-hormone-receptor superfamily that are activated by various lipid species--in regulating inflammatory responses. Here, we describe how the PPARs, through their interactions with transcription factors and other cell-signalling systems, have important regulatory roles in innate and adaptive immunity.

Uncoupling of growth plate maturation and bone formation in mice lacking both Schnurri-2 and Schnurri-3.

Formation and remodeling of the skeleton relies on precise temporal and spatial regulation of genes expressed in cartilage and bone cells. Debilitating diseases of the skeletal system occur when mutations arise that disrupt these intricate genetic regulatory programs. Here, we report that mice bearing parallel null mutations in the adapter proteins Schnurri2 (Shn2) and Schnurri3 (Shn3) exhibit defects in patterning of the axial skeleton during embryogenesis. Postnatally, these compound mutant mice develop a unique osteochondrodysplasia. The deletion of Shn2 and Shn3 impairs growth plate maturation during endochondral ossification but simultaneously results in massively elevated trabecular bone formation. Hence, growth plate maturation and bone formation can be uncoupled under certain circumstances. These unexpected findings demonstrate that both unique and redundant functions reside in the Schnurri protein family that are required for proper skeletal patterning and remodeling.

SAHA Enhances Differentiation of CD34+CD45+ Hematopoietic Stem and Progenitor Cells from Pluripotent Stem Cells Concomitant with an Increase in Hemogenic Endothelium.

Epigenetic modification is an important process during hematopoietic cell differentiation. Histone deacetylase (HDAC) inhibitors have previously been shown to enhance expansion of umbilical cord blood-derived hematopoietic stem cells (HSCs). However, the effect of HDAC inhibitors on pluripotent stem cells (PSCs) in this context is less understood. For years, investigators have considered PSC-derived natural killer (NK) and T-cell therapies. These "off-the-shelf" cellular therapies are now entering the clinic. However, the in vitro commitment of PSCs to the hematopoietic lineage is inefficient and represents a major bottleneck. We investigated whether HDAC inhibitors (HDACi) influence human PSC differentiation into CD34+CD45+ hematopoietic stem and progenitor cells (HSPCs), focusing on hemogenic endothelium (HE). Pluripotent stem cells cultured in the presence of HDACi showed a 2-5 times increase in HSPCs. Concurrent with this, HDACi-treated PSCs increased expression of 7 transcription factors (HOXA5, HOXA9, HOXA10, RUNX1, ERG, SPI1, and LCOR) recently shown to convert HE to HSPCs. ChIP-qPCR showed that SAHA upregulated acetylated-H3 at the promoter region of the above key genes. SAHA-treated human PSC-derived CD34+CD45+ cells showed primary engraftment in immunodeficient mice, but not serial transplantation. We further demonstrate that SAHA-derived HSPCs could differentiate into functional NK cells in vitro. The addition of SAHA is an easy and effective approach to overcoming the bottleneck in the transition from PSC to HSPCs for "off-the-shelf" cellular immunotherapy.

Pharmacologic targeting of a stem/progenitor population in vivo is associated with enhanced bone regeneration in mice.

Drug targeting of adult stem cells has been proposed as a strategy for regenerative medicine, but very few drugs are known to target stem cell populations in vivo. Mesenchymal stem/progenitor cells (MSCs) are a multipotent population of cells that can differentiate into muscle, bone, fat, and other cell types in context-specific manners. Bortezomib (Bzb) is a clinically available proteasome inhibitor used in the treatment of multiple myeloma. Here, we show that Bzb induces MSCs to preferentially undergo osteoblastic differentiation, in part by modulation of the bone-specifying transcription factor runt-related transcription factor 2 (Runx-2) in mice. Mice implanted with MSCs showed increased ectopic ossicle and bone formation when recipients received low doses of Bzb. Furthermore, this treatment increased bone formation and rescued bone loss in a mouse model of osteoporosis. Thus, we show that a tissue-resident adult stem cell population in vivo can be pharmacologically modified to promote a regenerative function in adult animals.

Regulation of bone formation and immune cell development by Schnurri proteins.

Although identified over a decade ago, the function and physiological significance of the mammalian Schnurri protein family remained largely unknown. However, the recent generation and characterization of mice bearing null mutations in the individual Schnurri genes has led to the discovery of unexpected yet central roles for these large zinc-finger proteins in several biological processes. Here, we review findings of these studies and discuss the importance of the Schnurri protein family in regulating both the immune and skeletal systems.

Human innate lymphoid cell precursors express CD48 that modulates ILC differentiation through 2B4 signaling.

Innate lymphoid cells (ILCs) develop from common lymphoid progenitors (CLPs), which further differentiate into the common ILC progenitor (CILP) that can give rise to both ILCs and natural killer (NK) cells. Murine ILC intermediates have recently been characterized, but the human counterparts and their developmental trajectories have not yet been identified, largely due to the lack of homologous surface receptors in both organisms. Here, we show that human CILPs (CD34+CD117+α4ß7+Lin-) acquire CD48 and CD52, which define NK progenitors (NKPs) and ILC precursors (ILCPs). Two distinct NK cell subsets were generated in vitro from CD34+CD117+α4ß7+Lin-CD48-CD52+ and CD34+CD117+α4ß7+Lin-CD48+CD52+ NKPs, respectively. Independent of NKPs, ILCPs exist in the CD34+CD117+α4ß7+Lin-CD48+CD52+ subset and give rise to ILC1s, ILC2s, and NCR+ ILC3s, whereas CD34+CD117+α4ß7+Lin-CD48+CD52- ILCPs give rise to a distinct subset of ILC3s that have lymphoid tissue inducer (LTi)-like properties. In addition, CD48-expressing CD34+CD117+α4ß7+Lin- precursors give rise to tissue-associated ILCs in vivo. We also observed that the interaction of 2B4 with CD48 induced differentiation of ILC2s, and together, these findings show that expression of CD48 by human ILCPs modulates ILC differentiation.

Varicella Zoster Virus Induces Differential Cell-Type Specific Responses in Human Corneal Epithelial Cells and Keratocytes.

Purpose: While VZV DNA and antigen have been detected in acute and chronic VZV keratitis, it is unclear whether productive infection of corneal cells is ongoing or whether residual, noninfectious VZV antigens elicit inflammation. Herein, we examined VZV-infected primary human corneal epithelial cells (HCECs) and keratocytes (HKs) to elucidate the pathogenesis of VZV keratitis. Methods: HCECs and HKs were mock- or VZV infected. Seven days later, cells were examined for morphology, proinflammatory cytokine and matrix metalloproteinase (MMP) release, ability to recruit peripheral blood mononuclear cells (PBMCs) and neutrophils, and MMP substrate cleavage. Results: Both cell types synthesized infectious virus. VZV-infected HCECs proliferated, whereas VZV-infected HKs died. Compared to mock-infected cells, VZV-infected HCECs secreted significantly more IL-6, IL-8, IL-10, and IL-12p70 that were confirmed at the transcript level, and MMP-1 and MMP-9; conditioned supernatant attracted PBMCs and neutrophils and cleaved MMP substrates. In contrast, VZV-infected HKs suppressed cytokine secretion except for IL-8, which attracted neutrophils, and suppressed MMP release and substrate cleavage. Conclusions: Overall, VZV-infected HCECs recapitulate findings of VZV keratitis with respect to epithelial cell proliferation, pseudodendrite formation and creation of a proinflammatory environment, providing an in vitro model for VZV infection of corneal epithelial cells. Furthermore, the proliferation and persistence of VZV-infected HCECs suggest that these cells may serve as viral reservoirs if immune clearance is incomplete. Finally, the finding that VZV-infected HKs die and suppress most proinflammatory cytokines and MMPs may explain the widespread death of these cells with unchecked viral spread due to ineffective recruitment of PBMCs.

Biomechanical and Bone Material Properties of Schnurri-3 Null Mice.

Schnurri-3 (Shn3) is an essential regulator of postnatal skeletal remodeling. Shn3-deficient mice (Shn3-/-) have high bone mass; however, their bone mechanical and material properties have not been investigated to date. We performed three-point bending of femora, compression tests of L3 vertebrae. We also measured intrinsic material properties, including bone mineralization density distribution (BMDD) and osteocyte lacunae section (OLS) characteristics by quantitative backscatter electron imaging, as well as collagen cross-linking by Fourier transform infrared microspectroscopy of femora from Shn3-/- and WT mice at different ages (6 weeks, 4 months, and 18 months). Moreover, computer modeling was performed for the interpretation of the BMDD outcomes. Femora and L3 vertebrae from Shn3-/- aged 6 weeks revealed increased ultimate force (2.2- and 3.2-fold, p < .01, respectively). Mineralized bone volume at the distal femoral metaphysis was about twofold (at 6 weeks) to eightfold (at 4 and 18 months of age) in Shn3-/- (p < .001). Compared with WT, the average degree of trabecular bone mineralization was similar at 6 weeks, but increased at 4 and 18 months of age (+12.6% and +7.7%, p < .01, respectively) in Shn3-/-. The analysis of OLS characteristics revealed a higher OLS area for Shn3-/- versus WT at all ages (+16%, +23%, +21%, respectively, p < .01). The collagen cross-link ratio was similar between groups. We conclude that femora and vertebrae from Shn3-/- had higher ultimate force in mechanical testing. Computer modeling demonstrated that in cases of highly increased bone volume, the average degree of bone matrix mineralization can be higher than in WT bone, which was actually measured in the older Shn3-/- groups. The area of 2D osteocyte lacunae sections was also increased in Shn3-deficiency, which could only partly be explained by larger remnant areas of primary cortical bone. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Lentivirus delivery of shRNA constructs into osteoblasts.

Osteoblasts are the sole cell responsible for bone formation in vivo (1). Although genetic techniques have been extremely valuable to study the functions of certain genes in these cells in vivo, this approach is time consuming and expensive. An alternative loss-of-function approach that has been validated in many mammalian systems is shRNA-mediated gene silencing. This chapter describes methodology designed to introduce shRNA constructs into primary murine osteoblasts ex vivo in order to quickly assess the function of genes in osteoblast differentiation and extra cellular matrix mineralization. Both the production of shRNA-expressing lentiviruses and the infection of calvarial osteoblasts with these lentiviruses are detailed.